Native speakers of English naturally differentiate tense-lax vowels (e.g. /i:/ in FEAST vs. /ɪ/ in FIST) in their speech. Can the speakers of Bangla, Hindi and Japanese as a first language (L1) learning and using English as a second language (L2) maintain such contrastive vowel qualities? Hence, this study investigates L1 Bangla speakers' pronunciation of English tense-lax vowels. Data collected from recordings of a reading passage and a set of sentences by 19 speakers are analysed using Pratt, focusing on the contrast between traditionally paired English monophthongs /i:/ vs. /ɪ/, /u:/ vs. /ʊ/, /ͻ:/ vs. /ɒ/ and /ɑ:/ vs. /ʌ/ in terms of their length and high-low/front-back articulatory qualities. The findings suggest that the participants seem not to distinguish between these paired monophthongs in terms of their high-low/front-back qualities; although they mostly demonstrate maintaining their long-short features. Besides, these paired vowels appear to contrast to some extent on gender variation.