ABSTRACT While the number of stars in the Galactic bulge with detailed chemical abundance measurements is increasing rapidly, the inner Galactic bulge ($|b| \lt 2^{\circ }$) remains poorly studied, due to heavy interstellar absorption and photometric crowding. We have carried out a high-resolution IR spectroscopic study of 72 M giants in the inner bulge using the CRIRES (ESO/VLT) facility. Our spectra cover the wavelength range of 2.0818–2.1444 $\mu $m with the resolution of R ∼ 50  000 and have signal-to-noise ratio of 50:100. Our stars are located along the bulge minor axis at l  =  0°, b=  ±0°, ±1°, ±2°, and +3°. Our sample was analysed in a homogeneous way using the most current K-band line list. We clearly detect a bimodal metallicity distribution function with a metal-rich peak at $\rm \sim +0.3\,dex$ and a metal-poor peak at $\rm \sim -0.5\,dex$ and no stars with Fe/H > +0.6 dex. The Galactic Centre field reveals in contrast a mainly metal-rich population with a mean metallicity of $\rm +0.3\,dex$. We derived Mg/Fe and Si/Fe abundances that are consistent with trends from the outer bulge. We confirm for the supersolar metallicity stars the decreasing trend in Mg/Fe and Si/Fe as expected from chemical evolution models. With the caveat of a relatively small sample, we do not find significant differences in the chemical abundances between the Northern and the Southern fields; hence, the evidence is consistent with symmetry in chemistry between North and South.