The yellow-tail (Mugil galapagensis) and black-tail mullet (M. thoburni) are the Galapagos artisanal finfish fishery's most commercially important mugilids species. Despite this, knowledge about their biological characteristics is scarce and limited. In this study, the basic biological parameters of M. galapagensis and M. thoburni were estimated using empirical equations for combined sex based on total length (TL, cm) data from landings on Santa Cruz Island. The von Bertalanffy growth parameters for M. galapagensis were L∞ = 69.14 cm TL, k = 0.204 yr-1, ϕ' = 2.989, and t0 = -0.658 years, and for M. thoburni were L∞ = 62.26 cm TL, k = 0.218 yr-1, ϕ' = 2.927 and t0 = -0.631 years. The size (L50%) and age (t50%) at maturity was estimated at 35.80 cm TL (2.92 years) and 32.41 cm TL (2.74 years) for M. galapagensis and M. thoburni, respectively. The theoretical maximum age (tmax) and natural mortality (M) for M. galapagensis were 12.28 years and 0.32 yr-1, respectively. While for M. thoburni both parameters were 11.28 years and 0.35 yr-1. In conclusion, both mugilids species have slow growth, reach sexual maturity at about three years, are moderately long-lived, and have a slightly high natural mortality.