Mycosphaerella graminicola causes one of the most damaging diseases of wheat. M. graminicola has a large arsenal of secreted proteins expressed during infection that includes Candidate Effectors (CE, n ≥ 171) (do Amaral et al. 2012). However, it remains unclear how CEs facilitate the initial symptomless phase, support fungal invasion and trigger the formation of necrotic sporulating lesions. Using the annotated IPO323 reference genome (Goodwin et al. 2012), we selected 27 genes encoding small secreted proteins (i.e. MgSSPs) likely specifically expressed during infection according to EST data. We explored the temporal expression of these genes by quantitative RT-PCR during compatible and incompatible interactions. We confirmed that most selected MgSSPs (75%) are over-expressed (10 to 8000 fold) during plant infection compared to mycelium grown in vitro and could be classified fined groups into according to their expression profile during infection. Most MsSSPs (75%) have their maximum of expression during the late symptomless phase (7-10 days post-inoculation, dpi), with a dramatic decrease in expression at early stages of lesion formation (≥ 14 dpi). These effectors could be classified in two groups according to their expression profile during incompatible infection. One subgroup correspond to MgSSPs that are not expressed in incompatible interactions. This expression pattern was also observed for the known chitin-binding effector ECP6 required for infection (Marshal et al. 2011). Such effectors might be involved in endophytic growth or plant defense suppression during the symptomless phase. Other MgSSPs were as expressed in incompatible and compatible interactions. Such effectors might be involved in epiphytic growth on the leaf surface, since the fungus did not enter into leaf tissues in the interaction studied. Finally few MgSSPs (15 %) have their maximum of expression during the necrotic symptom phase associated with exponential fungal growth. One MgSSP was expressed during the switch to necrotrophy (10-14 dpi), while two others were only expressed during the necrotic phase (14-21 dpi). These effectors might play a role in triggering necrotic symptom, massive leaf colonization or pycnidia formation. The functional analysis of some of these genes is underway to validate their role during leaf colonization and infection.