We have optically and structurally investigated the effect of the barrier alloy composition and number of wells in strain compensated InGaAsP/InP multiquantum well (MQW) samples grown by low-pressure metalorganic vapor phase epitaxy that emit close to 1.55 μm. Low temperature photoluminescence (PL) spectra exhibited two additional anomalous emission lines, below the fundamental QW transition. The PL temperature evolution of such anomalous transitions deviates significantly from the bulk-like band gap behavior expected. Cross-sectional transmission electron microscopy (XTEM) shows that partial elastic relaxation, characterized by localized surface deformations (like surface channels) and/or interfacial undulations occurs for all samples in which anomalous PL lines are observed. TEM results also show that the extra PL lines are correlated to neither Cu-Pt type atomic ordering in the well/barrier layers nor to phase separation. These anomalous transitions are tentatively attributed to the presence of interfacial undulation as well as to surface deformation and to the presence of interfacial domains with an intermediary composition between those of the barrier and QW layers.