While having a close look at the concept of stopwords, the researchers examined 30 chemistry scientific articles published in high ranking Persian journals to find an answer to the following research questions: (1) Should all punctuation marks, numbers, and English letter combinations (letter-number and letter-punctuationnumber combinations) be included in the stoplist and thus be eliminated as candidates for indexing? (2) Is it correct to change all upper case letters into lower case letters, i.e., to downcase letters? And (3) Could Persian be dealt with in automatic indexing without making reference to the characteristics of English? The manual analysis of the sample revealed that the omission of all punctuation marks, numbers, etc. will have a negative effect on recall, since punctuation marks, particularly ‘dot’ and ‘hyphen’ appear in the structure of content-bearing elements and even appear abundantly in titles and abstracts of scientific articles. With regard to downcasing, or unifying all upper and lower case letters, the conclusion was that it is much more restricted in Persian compared to English and that some possible places where it may cause problems are the structure of formulas, names of chemical substances, acronyms and proper nouns. Finally, it was found that because of the appearance of English letters, words, numbers, etc. in the body of Persian articles, some characteristics of the English language must also be considered while working on automatic indexing of Persian articles. The overall conclusion was that some sort of compromise is required in labeling numbers, punctuation, acronyms, etc. as either stopwords or content-bearing elements and thus as potential index candidates. Key terms: computational linguistics, automatic indexing, stopword, stoplist, noise, chemistry articles, punctuation, number, Persian, Farsi, English Abstracto Teniendo en cuenta el concepto de las palabras conocidas como “stopwords”, unos investigadores examinaron 30 articulos cientificos sobre quimica publicados en diarios persas competitivos para asi poder encontrar una respuesta a las siguientes preguntas: (1) ?Deberian ser incluidos todos los signos de puntuacion, numeros y combinaciones de letras en ingles (letra con numero y letra con signo de puntuacion y numero) en la “stoplist” y por ende ser eliminados de los indices? (2) ?Es correcto cambiar todas las letras mayusculas a minusculas? Y (3) ?El persa puede utilizarse en indices automaticos sin hacer referencias a las caracteristicas del ingles? El manual de analisis de la muestra revela que la omision de los signos de puntuacion, numeros, etc. tendria un efecto negativo ya que los signos como el punto y el guion aparecen en la estructura de los elementos que incluyen contenido y hasta aparecen de manera abundante en titulos y abstractos en articulos cientificos. Con relacion a la minusculizacion de las letras o la union de las letras mayusculas y minusculas, la conclusion fue que la variacion es mas estricta en el persa que en el ingles y que en