Labialization and pharyngealization are secondary articulations that are produced with different vocal tract modifications. In Tashlhiyt, a language that has both secondary articulations in its consonant system, labialization is produced with lip protrusion and a backing of the tongue, while pharyngealization is articulated by a backward movement of the tongue towards the pharynx. Despite this difference, both secondary articulations are reported to have similar acoustic effects regarding F2 across languages. The current study investigates the impact of labialization and pharyngealization on the formant structure of adjacent vowels in the same language. The analysis of VCV logatomes containing /i, a, u/ produced by 35 Tashlhiyt speakers revealed that both secondary articulations show equivalent patterns related to F2, which are strongest in /i/, followed by /a/, whereas differences between labialization and pharyngealization depend mainly on F1 and vowel quality.