The structural, transport, magnetic, and optical properties of high-pressure-synthesized metastable compounds CrGaSb and CrGa2Sb2 are calculated from first principles. In addition to theoretical results, new X-ray structural measurements of CrGa2Sb2 up to 9 GPa are reported. Both high-pressure phases CrGaSb and CrGa2Sb2 are found to be at the edge between metal and semiconductor, which implies that the standard density functional theory predictions may be misleading. To clarify the situation, a study is conducted whether the results depend significantly on the approximation used for the exchange–correlation potential. A possible effect of slight nonstoichiometry found in the CrGa2Sb2 samples is also investigated. The calculation results agree with most available experimental data and are internally consistent, which provides the assurance that, as a whole, they give a reliable picture of electronic properties in CrGaSb and CrGa2Sb2. © 2012 Wiley Periodicals, Inc.